Back in 2022, a law passed in California that allowed cities more flexibility in setting their speed limits. Prior to AB 43’s passage, speed limits were subject to a phenomenon known as “speed creep,” where speeding drivers led to cities having to raise posted speed limits, continuing a vicious cycle. This new law allowed greater flexibility in setting limits, particularly in areas with a history of crashes or on roads with a significant amount of bicycle and pedestrian activity.
Happily, a number of Marin’s cities and towns have taken advantage of this new flexibility to lower speed limits on highly trafficked roads or those with a history of crashes. Corte Madera is the standout here, with limits lowered across town. San Rafael has lowered limits in the downtown and on 2nd Street, and Marin County recently lowered the speed limit on San Geronimo Valley Road where the tragic crash occurred in April of 2025.
Unfortunately, not every city in Marin has gotten the memo. The City of Mill Valley went through the effort of updating speed limits (which allows for police to enforce them with radar) across the city this past January, but failed to take advantage of the newfound flexibility under AB 43. Two opportunities for improving bicycle safety in particular stood out to us, namely Miller Avenue and Camino Alto. Both of these roads are extremely well traveled by bicyclists and were identified as being on the “High Collision Network” in Marin’s recent Local Road Safety Plan. E. Blithedale Avenue between Throckmorton and Millwood, while not as well used by bicyclists (but an important pedestrian link), was evaluated for speed limits changes as well.
Unfortunately, the Department of Public Works neglected to employ the provision in state law that Corte Madera used so effectively, namely the ability to lower speed limits by an additional 5 mph if a road is “adjacent to any land or facility that generates high concentrations of bicyclists or pedestrians.” Using this statute, CVC 22358.7.a.2, would have allowed Camino Alto and Miller Avenue to be brought down from their current 30 mph to a more reasonable 25 mph. E. Blithedale Avenue west of Millwood Avenue could likely have gone down to 20 mph, the speed limit that San Rafael has set for 4th Street and much of downtown.
According to the Vision Zero Network, “Managing speeds is the #1 priority to advance Vision Zero.” Lowering posted speed limits, which has a clear and measurable effect on the speeds that drivers travel, reduces both the likelihood of collisions occurring and the severity of collisions when they do take place.
We are sympathetic to staff at the DPW, who (like many of their colleagues around the county) are overworked and understaffed. This miss may have simply been the result of poor advice from the consulting engineers who managed the speed survey for the city. A reason given to us from staff was that lowering posted limits would have required “much more outreach to the community.” We believe that, when safety is on the line, the experts should lead rather than putting speed limits up for debate. The reforms in Corte Madera, San Rafael, and unincorporated county went before the governing bodies, but were not the subject of a long, drawn-out public input process. To our knowledge, there has been no subsequent blowback.
Regardless, the outcomes are clear – a missed opportunity to lower vehicle speeds on three critical corridors identified as safety hazards in the county’s own Local Road Safety Plan. In order to improve safety for Mill Valley residents and the many people using its streets, we urge the City Council to direct staff to take another look at this, and to employ these hard-won tools for local control in future roadway safety efforts.
Click here to send an email to the Mill Valley City Council saying you want to see lower speed limits on Camino Alto and Miller Avenue.